Objective: To observe the expression and significance of fibronectin and metalloproteinase-3 (MMP-3) in patients with ankylosing spondylitis (AS). Methods: A total of 30 AS patients in our hospital and 30 healthy volunteers were selected in our study. Fibronectin and MMP-3 were measured and compared between these two groups. The AS group received sulfasalazine 2 g daily for 3 months. Bath ankylosing spondylitis disease activity index, bath ankylosing spondylitis functional index, bath ankylosing spondylitis metrology index, erythrocyte sedimentation rate and C-reactive protein were compared before and after treatment. Pearson's linear-correlation analysis was used to determine relationships between parameters. Results: Totally 28 patients in the AS group completed the study. Fibronectin and MMP-3 in peripheral blood of AS patients were evidently higher than that in the normal control group (P<0.05). After treated by sulfasalazine, the level of expressing Fibronectin and MMP-3 significantly decreased compared with baseline values (P<0.05). Pearson's linear-correlation analysis showed that serum fibronectin and MMP-3 level had a positive correlation with bath ankylosing spondylitis disease activity index global assessment, spine pain, night pain, general pain, erythrocyte sedimentation rate and C-reactive protein (P<0.05). Conclusions: The expression of fibronectin and MMP-3 in AS patients were significantly higher than that in the normal control group, and they all decreased significantly after treatment. It indicated that both fibronectin and MMP-3 were correlated closely with the onset of AS.